TM 5-3805-291-23-1
THEORY OF OPERATION - CONTINUED
0003 00
ENGINE - CONTINUED
4.
Crankshaft.
a.
Crankshaft converts linear piston motion into rotational motion. Crankshaft drives a group of gears (front gear
train) on engine's front. Front gear train provides power for these components:
Camshaft
Water pump
Engine oil pump
Fuel transfer pump
Accessory drive
b.
Crankshaft is held in place by seven main bearings. Oil holes and grooves in shells of upper bearings supply oil to
connecting rod bearings. Connecting rod bearing oil holes are located in main bearing journals 2, 3, 5, and 6.
c.
Hydrodynamic seals are used at both ends of crankshaft to control oil leakage. Hydrodynamic grooves in seal lips
move lubrication oil back into crankcase as crankshaft turns. Front seal is located in engine front housing. Rear
seal is installed in flywheel housing.
5.
Camshaft.
a.
Camshaft has three lobes at each cylinder to operate fuel injector, exhaust valves, and inlet valves. Seven bearings
support camshaft, which is driven by an idler gear turned by crankshaft in front gear train. Each bearing journal is
lubricated from oil manifold in cylinder block. A thrust pin located at rear of block positions camshaft through a
circumferential groove. Groove is machined at rear of camshaft. Camshaft timing is accomplished by aligning
marks on crankshaft gear, idler gear, and camshaft gear.
b.
Camshaft injector lobe has a modified profile. Modified profile produces multiple injections.
6.
Vibration Damper. Combustion force from cylinders and driveline components will cause crankshaft to twist. This is
called torsional vibration. If vibration is severe, crankshaft will be damaged. Driveline components can excite torsional
stress, which can damage components. Vibration damper limits torsional vibrations to an acceptable level to prevent
damage to crankshaft.
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